A method and apparatus for rapid growth of diamond films is known as described in Akatsuka et al., Japanese Journal of Applied Physics, Volume 27, No. 9, Sept., 1988, pages L1600 to L1602. In this prior art method, the electrodes arranged in a vacuum in a reaction chamber serve exclusively to generate a vacuum discharge arc and the substrate to be coated is arranged on a holder disposed below the direct current arc fired between the electrodes A gas mixture composed of hydrogen and argon is introduced into the arc by way of a gas inlet disposed outside of the region of the electrodes. This gas mixture further includes ethanol which is used as a carbon source A drawback of this prior art method is that, with the use of gaseous hydrocarbons, carbon and hydrogen occur coupled to one another and do not vary completely independent of one another during the process; the same also applies for oxygen if ethanol is used. Moreover, the external supply of gas brings with it a larger percentage of neutral gases.
German Patent No. 3,413,891, which corresponds to U.S. Pat. No. 4,917,786, discloses a method and an apparatus for evaporating material in a vacuum chamber equipped with an anode which evaporates under the influence of a direct current arc. Both electrodes may be composed of graphite or may at least be coated with graphite. In a region facing the anode, the cathode has a considerably larger diameter than the anode.
In contrast to the method described in the Japanese periodical, this prior art vacuum discharge arc is maintained essentially by the fuel material produced by the evaporating anode components. Above the electrode pair, that is, outside of the region of the arc, there is provided a vapor-deposition chamber accommodating the substrate in which, if necessary, a reactive gas atmosphere is maintained to influence the vapor deposition process. However, this disclosed vacuum arc is unable to generate in sufficient quantities the atomic hydrogen and/or H.sup.+ ions required for the production of diamond layers.